/**
 * File BounceInterpolator.java
 * ---------------------------------------------------------
 *
 * Copyright (C) 2012 David Bauske (david.bauske@googlemail.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package net.cl.util.anim;

/**
 * Performs a bouncy interpolation.
 *
 * Note that this class is a enum-based singleton. Use
 * BounceInterpolator.INSTANCE to obtain the class's instance.
 *
 * @author David
 */
public enum BounceInterpolator implements Interpolator
{
	INSTANCE;

	private static final double			BOUNCYNESS	= 9;

	/**
	 * This Bounce interpolation is quite interesting...
	 *
	 * Initial mathematical function:
	 * y(x) = -(abs(-(9(-x^4 + 1.0925x^3) -1))) + 1
	 *
	 * {@inheritDoc}
	 */
	@Override
	public double getInterpolationValue(
			double pPercentage,
			double pStartVal,
			double pEndVal)
	{
		double range = pEndVal - pStartVal;

		double value = -Math.pow(pPercentage, 4);	// -x^4
		value += 1.0925 * Math.pow(pPercentage, 3);	// + 1.0925*x^3
		value *= BOUNCYNESS;						// *9
		--value;									// - 1
		value = Math.abs(value);					// abs
		value = -value + 1;							// -(...) + 1

		return pStartVal + value * range;
	}

	@Override
	public String toString()
	{
		return getClass().getSimpleName();
	}
}
